Instant hot water boiler for shower..??

[CBW]

@muggles it is a 20A cable running to the building

@Johntheo5 I forgot to say that at this stage unfortunately cost is a huge factor as I have run out of money! so as far as I can see a cylinder from main manufacturer is into about £300.... this is why I as hoping to just get away with the instant boiler at around £100 and this one from germany wasn't too much more....
@oldbutnotdead no gas in the house either - everything is electric :/
@CBW thank you for those, so you reckon if I was to swap the thermostatic mixer for something like that it would work better on an instant boiler?

Thank you all for your help!

Imo, if the manual states it can’t be used with a thermostatic mixing valve, then a non thermostatic should work.

 

[Bohobee]

No such thing as a 20A cable, the current carrying capacity depends on cross section area, length, installation method and load type.
If the max current permitted is 20A you can forget all flash heaters except the small 3kw washbasin ones mentioned.
EDIT If £200 is a critical amount in your outbuilding build then you've been over optimistic with your budget
By now there is probably £10,000 or more invested in the thing, the phrase 'spoil the ship for a hap'orth of tar' springs to mind.
Is this going to be a revenue generating space or just a guest facility? If the former then a shoddy install will come back to bite you, if the latter the guests will have to cope with a trip to the house for a shower until you can afford to finish it properly.

Sorry I meant 20mm cable
At this stage I am not going to stop and leave things half finished. So something will be going in. but one can keep saying "it's only a couple of extra hundred" until forever - that's why most people are in debt!! I have set a strict budget now and out of that I need to also be able to clear up the mess in the garden that is left after the works have happened. That £100 here and there is the difference between walking through mud to get to it or being able to put a few bags of gravel down etc
I basically just need the cheapest option that will also do the job. It is purely for occasional guest use. But having gone to the trouble of fitting a shower room and upgrading the electrics to facilitate it then I would like it to be useable.
If swapping my thermsotaic mixer for a manual one means that the instant water heater will do the job, then that currently seems the cheapest option.
If I am being told that it is impossible to run a shower off an instant water heater then I either look at a storage type OR i go for an electric shower and seperate small instant water heater for the sinks - which still may be a cheaper option. (though also the most disruptive as we would need to reroute the wiring to the shower wall, plus the shower I have already bought becomes defunct )

 

[wundaboy]

The way I'd look at it is, are you going to be happy with an instant heater? Even the most powerful ones that can be installed on a UK domestic supply (generally 10.8kW) give a pretty underwhelming flow rate in the shower, particularly in winter when the incoming water supply is colder. It may be that you go for this option because it's cheaper now, decide down the line you don't like it and want something better, which with electric-only inevitably means a storage solution. It's potentially throwing good money after bad.

If it were me, I'd suffer the couple of hundred pounds of extra debt now in order to have a long term solution that I was happy with.

 

[cdbe]

You should have upgraded the cylinder in the house (the one that runs out).and run a continuous, insulated 15mm plastic pipe directly from cylinder to outhouse. Water moves pretty fast.

 

[Bohobee]

The way I'd look at it is, are you going to be happy with an instant heater? Even the most powerful ones that can be installed on a UK domestic supply (generally 10.8kW) give a pretty underwhelming flow rate in the shower, particularly in winter when the incoming water supply is colder. It may be that you go for this option because it's cheaper now, decide down the line you don't like it and want something better, which with electric-only inevitably means a storage solution. It's potentially throwing good money after bad.

If it were me, I'd suffer the couple of hundred pounds of extra debt now in order to have a long term solution that I was happy with.

thank you for your reply - I just don't understand how an electric heater doesn't just basically do the same thing as an electric shower? sorry If I'm being stupid, but I know plenty of folk with 8kw showers which are great... so if I go for say a 10-12kw instant water heater why wouldn't that do as good a job?? genuine question?
The other reason for wanting the instant rather than the stored water - is that 1) the building wil be used spontatneously - so wouldn't necassarily plan in advance and wouldn't want to be leaving a stored water heater turned on all the time just for the odd hand washing/glass rinsing useage (obviously showering is likely to be less spontaneous!) but as an added bonus I was also looking forward to having an instant solution for the times when myself and both kids want showers and we currently have to wait at least 30 min in between each...

 

[Bohobee]

You should have upgraded the cylinder in the house (the one that runs out).and run a continuous, insulated 15mm plastic pipe directly from cylinder to outhouse.

Not sure that would work! It's pretty big so to upgrade would mean a huge one! It only runs out if three of us have baths/showers in sequence so it needs time to refill inbetween. The whole point of putting a shower in the outbuilding is that if we do have guests they can actually shower without adding to the queue.

 

[Johntheo5]

There are tens of thousands of electric showers ranging from 8

thank you for your reply - I just don't understand how an electric heater doesn't just basically do the same thing as an electric shower? sorry If I'm being stupid, but I know plenty of folk with 8kw showers which are great... so if I go for say a 10-12kw instant water heater why wouldn't that do as good a job?? genuine question?
The other reason for wanting the instant rather than the stored water - is that 1) the building wil be used spontatneously - so wouldn't necassarily plan in advance and wouldn't want to be leaving a stored water heater turned on all the time just for the odd hand washing/glass rinsing useage (obviously showering is likely to be less spontaneous!) but as an added bonus I was also looking forward to having an instant solution for the times when myself and both kids want showers and we currently have to wait at least 30 min in between each...

There are tens of thousands of 8/10.5kw showers installed and people are perfectly happy with them, I have a 9kw, perfectly happy with its flowrate.
As stated above, a 9.5kw will flow 3.9/5.4LPM, winter/summer.
The first thing to establish is to ask your electrician what size cable he has installed.

 

[Bohobee]

There are tens of thousands of electric showers ranging from 8
There are tens of thousands of 8/10.5kw showers installed and people are perfectly happy with them, I have a 9kw, perfectly happy with its flowrate.
As stated above, a 9.5kw will flow 3.9/5.4LPM, winter/summer.
The first thing to establish is to ask your electrician what size cable he has installed.

20mm cable

 

[Johntheo5]

You mean 20mm2 cable??

 

[Bohobee]

You mean 20mm2 cable??

erm yes? I think! I asked the builder and he said 20mm...the whole reason for putting it in was to allow me to put in a decent instant hot water boiler, run heaters etc.. so it was meant to be a decent size ?

 

[Johntheo5]

If 20mm2 then fine.
There is a flow switch on these instant heaters but I don't see the actual setting on your attachments, you might consider giving Redring a buzz and ask them.

 

[Harry Bloomfield]

If 20mm2 then fine.
There is a flow switch on these instant heaters but I don't see the actual setting on your attachments, you might consider giving Redring a buzz and ask them.

There is no cable sized at 20mm, sizes around 20mm are 10, 16, 25, and 35mm.

 

[Johntheo5]

Cables are sized by their csa, cross sectional area, but are often referred to in mm

 

[Harry Bloomfield]

Cables are sized by their csa, cross sectional area, but are often referred to in mm

Eh?

 

[Johntheo5]

Harry, there are no cables sized 10,16,25 or 35 mm.